conf: deby.conf: Add $SDKPATH_DEFAULT to modify install path.
conf: deby.conf: Add $SDKPATH_DEFAULT to modify install path.

$SDKPATH is set to /usr/local/${SDK_NAME_PREFIX}-${SDK_ARCH}
by bitbake.conf unintentionally
if user don't overwrite $SDKPATH by other meta-xxx layer.

By adding $SDKPATH_DEFAULT,
meta-debian set $SDKPATH to /opt/${DISTRO}/${SDK_VERSION} by default.
If user would like to modify the install path,
overwrite $SDKPATH_DEFAULT by other meta-xxx layer.

Signed-off-by: Masahiro Yamada <76d6c03d331b29d77eaac66c3113243c4dd22703@toshiba.co.jp>

meta-debian/meta-debian,tienlee/meta-debian,meta-debian/meta-debian,tienlee/meta-debian,tienlee/meta-debian,tienlee/meta-debian,tienlee/meta-debian,meta-debian/meta-debian,tienlee/meta-debian,meta-debian/meta-debian,meta-debian/meta-debian,meta-debian/meta-debian